Glow plug



Sept. 19, 1933. H. I. A. DORNER ET AL GLOW PLUG Filed Jan. 31, 1930 HERNHNN .Z. EUUENEE.

:: the resistance wire is related with the electrode vide a glow plug structure in which-the length Patented Sept. 19, 1933 f GLOW PLUG Hermann I A;

Dorner and Adolph -Widmann,

Detroit, Mich, assignors, bymesne 'assign- 3 ments; to Packard Motor Car Company,- @Detroit, Mich, a corporation of Michigan Application January 31, 1930. Serial No. 424,987

7 Claims. ((31. 123-145) This invention relates ,to 7 internal combustion engines and more particularly to devices, known as glow plugs, for assisting the combustion .of fuel charges in Diesel type engines. 1

Glow plugs are provided with a resistance ,wire which is usually coiled in amore or less free relation and with thejends fixed one to the electrode and the other tothe plug body, the coil portion projecting into the main com bustion chamher with many types of engines. Diesel engines require a compression of approximately five hundred pounds per squareinch in the-cylinder in order to ignite the charge and, furthermore, the compressed air within the cylinder is usually revolved at a high speed so that fuel sprayed therein will be well distributed. It is the most enicient practice to place the loosely wound pcr-' tion of the glow plug resistance .wire into position where the fuel can besprayed thereagainst when it is introduced into the combustion charn ber, such fuel in high speed enginesbeing under a pressure of more thantwo thousandpcunds per square inch. It will thus be seen that due to the above conditions, the glow plug issubjectedto high compression and explosion pressures, to an intense heat, to the pressureof the fuel and the turbulence, and also inasmuch as the fuel is sprayed directly against the resistance wire',;it is subjected to thehighest temperature within the combustion chamber. These conditions maintain the resistance wire at ahigh'temperature, even when not connected with a source of 'elec-- trical supply, and while in such highly heated condition the eifect of pressure tends'to distort the free portion of the resistance wire and to loosen or break the wire at its' points of attachment, such loosening being-also caused by the diiference in the degree of expansion of the other glow plug elements. As a result, the'life of glow plugs with high speed Diesel types of, engines is very short, and an object of the invention is to provide a glow plug in which the life is materially increased over those now known.

Another object of our invention is to provide a glow plug in which an end of a resistance wire is attached to an electrode in a manner such that it will not readily become loose or broken.

A further object of our invention is to provide a glow plug in which an intermediate portion of so that vibration between such portion and the end fastened to the electrode is substantially eliminated.

A still further object of our invention is to pro- -with ahead 25 to which 'a toolc'an' be applied to of the air gap, adjacent the end ofjthe electrode projectinginto the engine cylinden fis very small These and other objects of the invention will; appear from the following description taken inconnection with the drawing, which forms a part6! of this specification, andin'whichzj Fig. 1 is a medial sectional view through a glow plug incorporating my'invention;

Fig. 2,is'.,an 'elevational viewjofthej same; H :Fig 3 isa sectional view takenj'on" line 3-3 of'Fig. 1. V j .7

Referring now tothe drawing by "Characters of reference, 10 represents a core fwhich will be termed ,theelectrode. The terminal member 1:1 surrounds one end of thelelectrode and a "flange Z 12 is formed on the end of the electrode to secure' the terminal in position ZTheoppos'ite end'l3' -mediate the terminal l'l and the .flange'l i. 1-nsulating disks l'l are telescopically; arranged around the sleeve; 16 adjacenttheffiangel ifahd are clamped .against'the flange by one of a pair of complementary/ collars 18 and.19

body 20 Serves 'as acarrierjror the'bthr elements of theglowplugand the electrodeextends through such body, anut 21 being "screwed into the bodyifi a manner such that it willjwedge the member 18 against theZmembe'rflQ, andse cure the insulation 17in position. The member s is; seated at its end against; a gasket. 2 2,iwhich Y bears against a shoulder 23 foi med'interiorlys of the body. A plurality of insulating ,disks24 encircle the sleeve 16, intermediate the member 18 V and the terminal 11, and a portion'of such disks aresurrounded by the hollow, nut 21; Th'ejend o f the body through which the enlarged portion of the electro'de extends is of a diameter suchthat there will be an-air gap around the electrode andfextending. onlyIna very short distance longi tudinally ofth'elglow plug The body is provided screw the plug into and out of an opening in an engine cylinder wall. g One end of a resistance wire .extends'into a recess 2,6 in the end wall of the body and is fixed, therein by a wedge element 27' pressed transversely of the end of the resistance wire. The other end of the resistancewire projects through a hole 28 in the electrode, such hole being off center and extending transversely of the axis of the electrodeand exteriorly of the body '20. The end 29 of the resistance 'wire extending'through the,

only a support while contact between the wire and the electrode electrode hole extends preferably in the same plane with the hole and is bent to conform with the shape of the electrode, the extreme end be ing welded to the electrode as indicated at 30. The bent end portion of the resistance wire is originally formed so that it is from the electrode, jacent the weld to shrink to the form of the electrode and thereby eliminate breakage which would be caused if the shrinkage were not allowed,

for. A portion 31 of the resistance wire is wound spirally from the hole 28 toward the end of the electrode and is coiled twice within the recess from which it extends a short distancebeyond the end of the electrode in the form of a loosely Wound coil, and then extends --in-a reverse direc-- tion in a coil of increasingdiameter telescoping the portion 31 which is closely associated with the electrode. A short length of the wire'portionfil,

where it projects from the electrode, is bent outwardly as indicated at 32 so thatitis. spaced from the electrode in a'manner providing resiliency. and an angle such that the wire is not subjected'tothe bending stresses due 'to vibration which would be present if it closely followed the -peripheral wall of theelectrod e at this point; The coiling of the wire closely around the electrode and, its passage through the hole provide the weld provides the sole through which the current passes.

It will be seen that we have provided asimple manner of," attaching the endof the resistance wire to the electrode so that it'will remain se timewithout becoming cure, during a' long period of engine operating loose and without breaking. Such results are. also assisted by-the manner in which theportion 31- of the wire is wound aroundthe electrode andseated tightly within the recess 15; Such arrangement permits'the loosev v ortion of the coil a "certain. degree" ofmovement and expansion without imparting bending stresses to the portion adjacentthat secured tothe, electrode and without disturbing the contact weld;

While we have herein a specific embodiment we deem to be new and advantageous andmay specifically claim, we'do not desire it to be un;- derstood that our invention islimited to the'exdescribed insome detail 7 act details oftheconstruction, as it will be aptially coiled against the electrode for support and 7 slightly spaced thus allowing the "portion adof our invention, whichfixed at one end to' the welded thereto for. a contact.

2. In a glow plug for internal combustion engines having a body and an insulated electrode projecting from the body, heating means comprising a resistance wire-fixed atone end to the body, a portion. of the wire being coiled closely around and projecting through the electrode with Q the end fixed to the electrode, a-portionof the wire coiled around the electrode adjacent the portion extending through the electrode and the closely coiled portion being bent to extend in spaced relation from the electrode. 3. In a glow-plug for internal combustion engines having a body. and an insulated electrode extending through the body, one end of the electrode having a portion. of reduced diameter form ing a recess, heating means comprising a resist .ance'wire having one end fixed to the body and the other end fixed to the electrode, a portion of the wire adjacent the end fixed to the electrode being coiled closely against the electrode in the recess.

4. In a glowplug for internal combustion en- "gines having a bodyand an electrode insulated from and extending through the body, one end of the electrode having a circular recess therearound, heating means comprising a resistance wire fixed atone end to the body and at theother end to the electrode adjacent the body, said wire adjacent the end fixed to the electrode being coiled closely against the electrode and in the recess and then continued as a coil inspaced rela tion from the electrode toward the end fixed to the body.

5. In a glow plug for'internal' combustion engines of the Diesel type having a body and an electrode projecting from the body, heating means'co'mprisinga resistance wire fixed at one end to the body and welded at the other end to the electrode to form the contact, said wirebeing supported in ashock absorbing relation upon the electrode adjacent the welded portion thereof. 6; In a glow plug'for internal combustion engines of the Dieseltype having a body and an electrode projecting from the body, heating means comprising aresistance wire fixed at one end to the body andwelded at the other end to the electrode to form a contact, the end of the wire adjacent-the welded portion beingcoiled close against the; electrode and passing transverlsely therethrough intermediate the endsofthe col I '7. In a glow plugfor internal combustionengines'of'the Diesel type having a body andan 

